A single bird in first winter
plumage was first located on 14 February 2014 by K. Terán and several other
observers at Yaguarcocha Lake, Imbabura Province, northern Ecuador (Nilsson et al. 2014). It remained at
the same site until 5 March 2014 and was observed and photographed by several
other birders.

Comments
from Jaramillo: “YES –
The features that are important are: 1) dark inner primaries 2) dark tail 3)
bicolored bill 4) dark and relatively unmarked greater coverts. Identification is
most problematic from smithsonianus
Herring Gull, and to a lesser extent (no pun intended) from Lesser Black-backed
Gull. But the photos identify the bird as a California Gull, particularly due
to the wing pattern, vs. smithsonianus,
and tail pattern vs. L. fuscus.”

Comments
from Zimmer: “YES,
although only based upon what can be seen in the (not great) photo, and not
from the rather scanty and misleading description (“more uniform pale
upperparts than Herring Gull”).I would
echo Alvaro’s analysis of the key distinguishing features, and add that the neatly
black-tipped, mostly pinkish bill is typical for 1st-cycle
California Gulls, and atypical for like-aged smithsonianus Herring Gulls.”

Comments
from Stiles: “YES. I
defer to Alvaro on this, as I am not an expert on gulls (living in landlocked
Bogotá).”

Comments
solicited from Jon Dunn:
“I judge the photo from Yaguarcocha Lake, Imbabura Province, northern
Ecuador, to be a first cycle California Gull, a conclusion reached by the
finding observers. I agree with their analysis, noting the rather small
parallel-sided bill that is bi-colored. The bill shape of our North
American smithsonianus, is more robust overall. One feature not
addressed by the reporting observers, but it is clinching for me is the lack of
a pale inner primary panel. Our Herring Gull, as well as European
subspecies of Herring, has a pale inner panel on the primaries. This is
almost completely lacking in first and second cycle California Gulls, and in
the one photo I evaluated, the entire upper wing is shown nicely, and it looks
to my eye just perfect for California. Young California Gulls have a very
dark ‘hand.’ There may some Old World taxon of Herring Gull (e.g. armenicus)
that may have a similar wing pattern. I haven’t researched all of the
‘Herring’ taxa for wing patterns of immatures, but this seems highly improbable,
and as noted the wing pattern fits California very closely. Another
feature, young first cycle California Gulls by mid and late winter look smudgy,
while first cycle Herring Gulls through the first winter look neater, somewhat
more scaly, etc., at least the ones that appear in western North America, in
general representing a later onset for the breeding season. Young
California Gulls are moving around by mid-July, and appear sometimes far from
breeding areas on that date. In other words by late winter they could
appear quite worn appearing. I would add, of course, that some first
cycle Herring Gulls, even in early winter, have a bi-colored bills, much like
Herring, although again the shape of the bill is different, and the line of
separation of pink and dark (more even in Herring) is slightly different.
As noted, bills are tricky, concentrate on that inner wing panel. Trust a
note will be published somewhere, perhaps in Cotinga?”